Date: 20 April 2000
To: UA List
From: Eric Hansen
Subject: Proposed definitions for content, document object, etc.
Comments on I. Jacob's proposals in
http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0132.html
I hope that the comments are helpful.
===========
1. Document Object
I. Jacobs (18 April):
<BLOCKQUOTE>
The document object is the user agent's representation
of resources retrieved from the Web. The data that makes up
the document object may have several origins, including
the document source (what is returned by an HTTP request
for a resource), generated content (from style sheets,
scripts, transformations, etc.), and user agent preferences.
</BLOCKQUOTE>
Comment by Eric:
1. I think one needs to make clear that it is not just any Web resources but
resources that pertain to the document.
New 1 by Eric Hansen:
<BLOCKQUOTE>
The document object is the user agent's representation of document-related
resources retrieved from the Web. The data that makes up the document object
may have several origins, including the document source (what is returned by
an HTTP request for a resource), generated content (from style sheets,
scripts, transformations, etc.), and user agent preferences.
</BLOCKQUOTE>
Comment 2 by Eric Hansen
2. However, this definition still seems to miss data like preferences
established by the user him or herself. Are those preferences intended to be
part of the document object? If so, it might be more correct to simply say
the following.
New 2 by Eric Hansen:
<BLOCKQUOTE>
The document object is the user agent's representation of the document. The
data that makes up the document object may have several origins, including
the document source (what is returned by an HTTP request for a resource),
generated content (from style sheets, scripts, transformations, etc.), and
preferences established by the user agent or by the user.
</BLOCKQUOTE>
============
2. Document object model.
I. Jacobs (18 April) wrote:
<BLOCKQUOTE>
A document object model is the abstraction that
governs the construction of the user agent's document
object. W3C's Document Object Model (DOM) specifies
a document object model for HTML and XML documents. The W3C
DOM specifies a standard interface for accessing HTML and XML
content. This standard interface allows authors to access and
modify the document with a scripting language (e.g., JavaScript)
in a consistent manner across scripting languages.
As a standard interface, a document object model makes
it easier not just for authors but for assistive technology
developers to extract information and render it in ways
most suited to the needs of particular users.
The relevant W3C DOM Recommendations are listed in the references.
</BLOCKQUOTE>
Comment 3 by Eric Hansen: This definition seems to merge the generic concept
of DOM in favor of W3C DOM. Since the requirement for adherence to the W3C
DOM is Priority 1. I suppose that is OK. I suggest the following:
New 1 by Eric Hansen
<BLOCKQUOTE>
A document object model is the abstraction that governs the construction of
the user agent's document object. The document object model employed by
different user agents will vary in implementation and sometimes in scope.
{EH comment: Is this correct?} Nevertheless, this document calls for
developers of user agents to adhere the W3C Document Object Model (DOM),
which specifies a standard interface for accessing HTML and XML content.
This standard interface allows authors to access and modify the document
with a scripting language (e.g., JavaScript) in a consistent manner across
scripting languages. As a standard interface, use of a W3C DOM makes it
easier not just for authors but for assistive technology developers to
extract information and render it in ways most suited to the needs of
particular users. The relevant W3C DOM Recommendations are listed in the
references.
</BLOCKQUOTE>
============
3. Content
<BLOCKQUOTE>
In this specification, the term "content" refers to the
document object. Some content is designed (by specification)
for "human consumption". For an HTML document, this includes
what appears between the start and end tags of elements, and
the values of some attributes (e.g., alt, title, summary).
Other content is meant for machines, including the markup
itself (e.g,. element and attribute names), some attribute
values (e.g., class, id, lang, src), style sheets, scripts,
etc.
</BLOCKQUOTE>
Comment by Eric Hansen: Isn't is correct that content is used several ways
but that a "_document's_ content" refers to the "document object".
Nevertheless, maybe your wording is OK.
Also, I think that the distinction between "for human consumption" and "not
for human consumption" is not as tight as the definition make it appear. Are
there not exceptions?
I have some nervousness about equating content with the document object. Are
there not cases where there are semantics that transcend a single document
concerns multiple documents (e.g., displayed in multiple frames [?]). But
perhaps this is OK.
New by Eric Hansen:
<BLOCKQUOTE>
In this specification, the "content" refers to the document object. Some
content is designed (by specification) for "human consumption". For an HTML
document, this typically includes what appears between the start and end
tags of elements, and the values of some attributes (e.g., alt, title,
summary). Other content is meant for machines, typically including the
markup itself (e.g,. element and attribute names), some attribute values
(e.g., class, id, lang, src), style sheets, scripts, etc.
</BLOCKQUOTE>
============
4. Equivalent alternatives for content
<BLOCKQUOTE>
Since <DEL>rendered</DEL> content in some forms is not always
accessible to users with disabilities, authors must specify
equivalent alternatives for content.
</BLOCKQUOTE>
Comment by Eric Hansen: Clarify that equivalent alternatives are not needed
for accessible content.
New by Eric Hansen:
<BLOCKQUOTE>
Since content in some forms is not always accessible to users with
disabilities, authors must provide equivalent alternatives for inaccessible
content.
</BLOCKQUOTE>
============
5) Rendered content
<BLOCKQUOTE>
The rendered content is that part of content that is
rendered in a given viewport (whether graphical, auditory,
or tactile).
</BLOCKQUOTE>
Comment by Eric Hansen: OK as given.
============
6. Source view
I. Jacobs (18 April):
<BLOCKQUOTE>
A source view renders all or part of the document
object in a way that reveals the document object
model. Often, a source view presents the document
object using the syntax of the source markup
languages.
</BLOCKQUOTE>
Comment by Eric Hansen: I am puzzled by the reference to the phrase: "in a
way that reveals the document object model".
The comments of Hans Riesebos seem sensible to me:
(From http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0154.html)
> > <Hans>
>> > As I understand, the "source" is unparsed and therefore cannot reveal
the
>> > document object in any way. Speaking of document object itself is
false.
>> If
>> > only the source was already parsed (contradiction in terms), a source
view
>> > might (minimally) satisfy checkpoint 2.1, because in effect it would
have
>> > become a document object view.
>> > </Hans>
>> >
>> > Hans Riesebos
>> > ALVA BV, The Netherlands
Comment by Eric Hansen: Isn't it possible to have a more commonsense of
source view? I am not sure what other issues ride on the definition of
source view. How about something like the following?
NEW
Source View:
A source view renders all or part of a document in a way that is close to
the representation of the document as was produced by the authoring tools. A
source view often presents textual representations of content.
============
7. User interface.
No comment.
============
8. View
I. Jacobs (18 April):
The term "view" is used in this document
to describe the purpose of a particular rendering (e.g.,
"outline view", "table of contents view", "links view").
Ian provided a later version
(http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0134.html) that
reads:
A view of content is a particular presentation of
a subset of that content. For instance, an "outline view"
of an HTML document might be created by filtering out
everything but the document's headings.
The latter version is an improvement.
====
===========================
Eric G. Hansen, Ph.D.
Development Scientist
Educational Testing Service
ETS 12-R
Princeton, NJ 08541
609-734-5615 (Voice)
E-mail: ehansen@ets.org
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